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D.15.6.5 grshift
Procedure from library gradedModules.lib (see gradedModules_lib).
- Usage:
- grshift(A, d), graded objects A, int d
- Return:
- shifted graded object
- Purpose:
- shift the grading on A by d: A(i) -> A(i+d)
Example:
| LIB "gradedModules.lib";
ring r=32003,(x,y,z),dp;
module A = grobj( module([x+y, x, 0, 0], [0, x+y, y, 0]), intvec(0,0,0,1) );
grview(A);
==> Graded homomorphism: r^3 + r(-1) <- r(-1)^2, given by a matrix, with degr\
ees:
==> ..1 ..2 ....
==> --- --- +...
==> 0 : 1 - |..1
==> 0 : 1 1 |..2
==> 0 : - 1 |..3
==> 1 : - - |..4
==> === ===
==> 1 1
module S = grshift( A, 6);
grview(S);
==> Graded homomorphism: r(6)^3 + r(5) <- r(5)^2, given by a matrix, with deg\
rees:
==> ..1 ..2 ....
==> --- --- +...
==> -6 : 1 - |..1
==> -6 : 1 1 |..2
==> -6 : - 1 |..3
==> -5 : - - |..4
==> === ===
==> -5 -5
grview( grshift( grzero(), 100 ) ); // does nothing...
==> !! Warning: shifting '0 <- 0' leaves it as it unchanged!
==> Graded homomorphism: 0 <- 0, given by zero (0^2) matrix.
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